Wireless Power Transmission Device and Operation Method Thereof

This application is a continuation of International Application No. PCT/KR2025/002435 designating the United States, filed on Feb. 20, 2025, in the Korean Intellectual Property Receiving Office and claiming priority to Korean Patent Application Nos. 10-2024-0045075, filed on Apr. 3, 2024, and 10-2024-0077456, filed on Jun. 14, 2024, in the Korean Intellectual Property Office, the disclosures of each of which are incorporated by reference herein in their entireties.

The disclosure relates to a wireless power transmission device, and an operation method thereof according to an embodiment.

Wireless power transmission technology using a magnetic induction method is a method of transferring power using an electromagnetic field induced in a coil, wherein a wireless power transmission device may generate an electromagnetic field by applying a current to a transmission coil, and an induced electromotive force is formed in a reception coil of a wireless power reception device due to the generated electromagnetic field, thereby enabling power to be transmitted wirelessly.

The wireless power reception device may perform in-band communication while receiving power wirelessly from the wireless power transmission device. The wireless power reception device may provide information to the wireless power transmission device by performing in-band communication. For example, the wireless power reception device may perform in-band communication, based on an amplitude shift keying (ASK) modulation method. The resonance circuit of the wireless power reception device may further include at least one element selectively connected via a switch, and the wireless power reception device may perform modulation by controlling the on/off state of the switch. Depending on the modulation in the wireless power reception device, the amplitude of the current and/or voltage applied to the transmission coil of the wireless power transmission device may be changed. The wireless power transmission device may identify the information provided by the wireless power reception device by demodulating and/or decoding the information about the amplitude of the current and/or voltage applied to the transmission coil.

Due to the presence of foreign objects, the power transmitted from the wireless power transmission device to the wireless power reception device may be lost. Foreign object detection techniques are required to increase the efficiency of power transmission.

According to an example embodiment, a wireless power transmission device may include: a transmission coil, at least one controller, comprising processing circuitry, and memory storing instructions, wherein at least one controller, may be configured to execute the instructions and to cause the wireless power transmission device to: receive first information from a wireless power reception device, wherein the first information may include information related to a transmission current of the transmission coil and mutual loss power; receive second information from the wireless power reception device, wherein the second information may include information related to a reception current of a reception coil of the wireless power reception device, a phase difference between the reception current and the transmission current, and/or a load resistance of the wireless power reception device; measure a first transmission current of the transmission coil; calculate first mutual loss power, based on the first information and the first transmission current; calculate first loss power, based on the first mutual loss power and the second information, wherein first loss power may include loss power generated by magnetic flux of the transmission coil, magnetic flux of the reception coil, and/or mutual magnetic flux connected between the transmission coil and the reception coil; measure second loss power between the wireless power transmission device and the wireless power reception device; and identify a foreign object, based on a difference between the first loss power and the second loss power being greater than or equal to a reference value.

According to an example embodiment, a method of operating a wireless power transmission device may include: receiving first information from a wireless power reception device, wherein first information may include information related to a transmission current of a transmission coil of the wireless power transmission device and mutual loss power; receiving second information from the wireless power reception device, wherein the second information may include information related to a reception current of a reception coil of the wireless power reception device, a phase difference between the reception current and the transmission current, and/or a load resistance of the wireless power reception device; measuring a first transmission current of the transmission coil; calculating first mutual loss power, based on the first information and the first transmission current; calculating first loss power, based on the first mutual loss power and the second information, wherein first loss power may include loss power caused by magnetic flux of the transmission coil, magnetic flux of the reception coil, and mutual magnetic flux connected between the transmission coil and the reception coil; measuring second loss power between the wireless power transmission device and the wireless power reception device; and identifying a foreign object, based on a difference between the first loss power and the second loss power being greater than or equal to a reference value.

According to an example embodiment, there may be provided a non-transitory computer-readable storage medium storing at least one instruction, wherein the at least one instruction, when executed by at least one controller, comprising processing circuitry, of a wireless power transmission device, causes the wireless power transmission device to perform at least one operation, comprising: receiving first information from a wireless power reception device, wherein the first information may include information related to a transmission current of a transmission coil of the wireless power transmission device and mutual loss power; receiving second information from the wireless power reception device, wherein the second information may include information related to a reception current of a reception coil of the wireless power reception device, a phase difference between the reception current and the transmission current, and/or a load resistance of the wireless power reception device; measuring a first transmission current of the transmission coil; calculating first mutual loss power, based on the first information and the first transmission current; calculating first loss power, based on the first mutual loss power and the second information, wherein the first loss power may include loss power caused by magnetic flux of the transmission coil, magnetic flux of the reception coil, and mutual magnetic flux connected between the transmission coil and the reception coil; measuring second loss power between the wireless power transmission device and the wireless power reception device; and identifying a foreign object, based on a difference between the first loss power and the second loss power being greater than or equal to a reference value.

According to an example embodiment, a wireless power transmission device may include: a transmission coil, at least one controller, comprising processing circuitry, and memory storing instructions, wherein at least one controller is configured to execute the instructions and to cause the wireless power transmission device to: receive first information from a wireless power reception device, wherein the first information may include information relating to an amount of electrical power applied to the transmission coil for providing wireless charging power in relation to an amount of mutual loss power caused by friendly metal interfering with mutual magnetic flux and the mutual magnetic flux may include magnetic flux connected between the transmission coil and a reception coil of the wireless power reception device; while providing wireless charging power through the transmission coil, identify second information relating to a first transmission current being applied to the transmission coil; identify third information relating to first loss power incurred while providing wireless charging power from the wireless power transmission device to the wireless power reception device; and while providing wireless charging power through the transmission coil, detect a foreign metal object, based on the first information, the second information, and the third information.

is a block diagram illustrating an example configuration of a wireless power transmission system including a wireless power transmission device and a wireless power reception device according to an embodiment.

Referring to, a wireless power transmission deviceaccording to an embodiment may wirelessly transmit powerto a wireless power reception device. Wireless power transmission may refer to a technology for transmitting power without a physical connection, and wireless charging technology includes, for example, an electromagnetic induction method using a coil, a resonance method using resonance, and a radio wave radiation (RF/microwave radiation) method that converts electrical energy into microwaves and transmits the same. The wireless power transmission devicemay transmit power according to the induction method, the resonance method, or the radio wave radiation method. The wireless power transmission devicemay be configured to perform wireless power transmission, based on at least one of the transmission methods of induction, resonance, or radio wave radiation. The wireless power transmission devicemay be configured to support all of the induction, resonance, or radio wave radiation methods. Wireless power transfer standards may include Qi (Chi) and PowerMat. Qi may include open technologies that allow electronic devices to wirelessly transfer power to and from each other. PowerMat may include technology that uses magnetic induction. Standards that use magnetic resonance may include, for example, and without limitation, Rezence, Hiper, WiPower, and the like. These methods may charge multiple devices at the same time. For example, the wireless power transmission devicemay transmit poweraccording to an induction method. When the wireless power transmission devicetransmits power by the induction method, the wireless power transmission devicemay include at least one of, for example, a power source, a direct current-to-direct current conversion circuit (e.g., a DC/DC converter), a direct current-to-alternating current conversion circuit (e.g., an inverter), an amplification circuit, an impedance matching circuit, at least one capacitor, at least one coil, or a communication modulation circuit. The at least one capacitor may form a resonance circuit together with the at least one coil. The wireless power transmission devicemay include a coil capable of generating an induced magnetic field when a current flows. The process by which the wireless power transmission devicegenerates the induced magnetic field may be described as the wireless power transmission devicewirelessly transmitting the power. In addition, an induced electromotive force (or, current, voltage, and/or power) may be generated in the coil of the wireless power reception deviceby the magnetic field generated in the surroundings according to an induction method. The process by which an induced electromotive force is generated by the coil may be described as the wireless power reception devicewirelessly receiving the power.

The wireless power transmission deviceaccording to an embodiment may perform communication with the wireless power reception device. The wireless power transmission devicemay exchange information with the wireless power reception device. For example, the wireless power transmission devicemay receive informationprovided from the wireless power reception device. The wireless power transmission devicemay provide the informationto the wireless power reception device. For example, the wireless power transmission devicemay perform communication with the wireless power reception deviceaccording to an in-band method. The wireless power transmission devicemay modulate data to be transmitted, for example, according to a frequency shift keying (FSK) modulation method, and the wireless power reception devicemay provide the informationby modulating the same according to an amplitude shift keying (ASK) modulation method. The wireless power transmission devicemay identify the informationprovided by the wireless power reception device, based on the amplitude of the current and/or voltage applied to the transmission coil. In, the wireless power reception deviceis shown as transmitting the informationdirectly to the wireless power transmission device, but this is simply for ease of understanding, and those skilled in the art will understand that the wireless power reception devicecontrols the on/off of at least one switch therein. The operation of performing modulation based on the ASK modulation method and/or the FSK modulation method may be understood as the operation of transmitting data (or packets) according to the in-band communication method, and the operation of performing demodulation based on the ASK demodulation method and/or the FSK demodulation method may be understood as the operation of receiving data (or packets) according to the in-band communication method.

is a is a perspective view illustrating an example wireless charging system according to an embodiment.

Referring to, a wireless charging system according to an embodiment may include a wireless power transmission deviceand a wireless power reception device. The wireless power transmission devicemay be a charging pad that transmits wireless power based on power supplied from a charger (e.g., travel adapter (TA)). According to an embodiment, the wireless power transmission devicemay be a device that includes a wireless power transmission function, for example, implemented as a smartphone, and the form of implementation is not limited thereto. The wireless power reception devicemay be an electronic device, such as a smartphone or wearable device, and is not limited in its implementation. According to an embodiment, the wireless power transmission deviceis not limited to a device that transmits wireless power, and the wireless power transmission devicemay include a function of transmitting wireless power and a function of receiving wireless power. According to an embodiment, the wireless power reception deviceis not limited to an embodiment of a device that receives wireless power, and the wireless power reception devicemay include a function of receiving wireless power and a function of transmitting wireless power.

is a block diagram illustrating an example configuration of of a wireless power transmission device and a wireless power reception device according to an embodiment.

Referring to, the wireless power transmission deviceaccording to an embodiment may include a controller (e.g., including processing circuitry). The wireless power transmission devicemay include memory. The wireless power reception devicemay include a controller (e.g., including processing circuitry). The wireless power reception devicemay include memory.

As used herein, performing a specific operation by the wireless power transmission deviceor the wireless power reception devicemay be understood to refer, for example, to various hardware included in the wireless power transmission deviceor the wireless power reception device, for example, the controllerorincluding, for example, (a micro controlling unit (MCU), a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), a microprocessor, or an application processor (AP)) performing a specific operation. Performing a specific operation by the wireless power transmission deviceor the wireless power reception devicemay be understood to refer, for example, to a controller (e.g., the controlleror) controlling other hardware to perform the specific operation. Performing a specific operation by the wireless power transmission deviceor the wireless power reception devicemay refer to causing the controller (e.g., the controlleror) or other hardware to perform the specific operation upon execution of at least one instruction for performing a specific operation stored in a storage circuit (e.g., memory (e.g., the memoryor)) of the wireless power transmission deviceor the wireless power reception device. The at least one instruction stored in memory (e.g., the memoryor) of the wireless power transmission deviceor the wireless power reception devicemay, when executed by the controller (e.g., the controlleror), cause the wireless power transmission deviceor the wireless power reception deviceto perform at least one operation. Where the controller (e.g., the controlleror) includes a processor, the processor may include various processing circuitry and/or multiple processors. For example, as used herein, including the claims, the term “processor” may include various processing circuitry, including at least one processor, wherein one or more of at least one processor, individually and/or collectively in a distributed manner, may be configured to perform various functions described herein. As used herein, when “a processor”, “at least one processor”, and “one or more processors” are described as being configured to perform numerous functions, these terms cover situations, for example and without limitation, in which one processor performs some of recited functions and another processor(s) performs other of recited functions, and also situations in which a single processor may perform all recited functions. Additionally, the at least one processor may include a combination of processors performing various of the recited/disclosed functions, e.g., in a distributed manner. At least one processor may execute program instructions to achieve or perform various functions.

Referring to, the wireless power transmission deviceaccording to an embodiment may include at least one of a transmission coil, an inverter, a converter, and/or a power source (e.g., power supply). The wireless power reception devicemay include at least one of a reception coil, a rectifier, a charger, and/or a battery.

Referring to, the drawing ofis illustrated.

is a circuit diagram of a wireless power transmission device and a wireless power reception device according to an embodiment.

According to an embodiment, the wireless power transmission devicemay include at least one of a power source, an inverterincluding a plurality of switches Q, Q, Q, and Q, a capacitor, a transmission coil, a demodulation circuit, a controller, and/or a DC/DC converter.

According to an embodiment, the power provided by the power sourcemay be provided to the DC/DC converter. The power sourcemay include at least one of an interface for connecting to an external travel adapter (TA), a battery (not shown) of the wireless power transmission device, a charger (not shown), or a power management integrated circuit (PMIC) (not shown). The power sourcemay provide direct current power to the DC/DC converter, for example, but is not limited to the type of power provided. The DC/DC convertermay convert the voltage of the provided power and provide the same to the inverter. The DC/DC convertermay change the voltage of the input DC power to provide DC power having the changed voltage (or, drive voltage (VDD)) to the inverter. The DC/DC convertermay perform buck conversion and/or boost conversion, for example, and may be implemented as a three-level converter, for example, but those skilled in the art will understand that the type of converter is not limited.

The inverteraccording to an embodiment may output alternating current power using the drive voltage VDD provided from the DC/DC converter. The plurality of switches Q, Q, Q, and Qmay form a full bridge circuit, for example, but there is no limitation on the number of switches or the type of bridge circuit. For example, when a full bridge circuit is configured, one end of the transmission coilmay be connected to a connection point between the switches Qand Qvia the capacitor, and the other end of the transmission coilmay be connected to a connection point between the switches Qand Q. The plurality of switches Q, Q, Q, and Qmay be controlled to be in an on state, or an off state. For example, in order to generate alternating current power, the controllermay control the first switch Qand the third switch Qto be turned on while controlling the second switch Qand the fourth switch Qto be turned off during a first period, may control the first switch Qand the third switch Qto be turned off while controlling the second switch Qand the fourth switch Qto be turned on during a second period, and may repeat the control operations described above. The controllermay provide control signals (Q_DRV, Q_DRV, Q_DRV, Q_DRV) for generating the alternating current power described above to the plurality of switches Q, Q, Q, and Q. Not only outputting a control signal, but also refraining from outputting a control signal may be referred to as a control of the controller. For example, outputting, by the controller, a first control signal for generating alternating current power having a first frequency to the invertermay be understood to refer, for example, to the controlleroutputting the control signals (Q_DRV, Q_DRV) for controlling the switches Qand Qto be turned on during a period corresponding to the first frequency, then outputs the control signals (Q_DRV, Q_DRV) for controlling the switches Qand Qto be turned on during the period corresponding to the first frequency, and repeats the output operations described above. On the other hand, outputting, by the controller, a second control signal for generating alternating current power having a second frequency to the invertermay be understood to refer, for example, to the controlleroutputting the control signals (Q_DRV, Q_DRV) for controlling the switches Qand Qto be turned on during a period corresponding to the second frequency, then outputs the control signals (Q_DRV, Q_DRV) for controlling the switches Qand Qto be turned on during the period corresponding to the second frequency, and repeats the output operations described above. In this case, the period corresponding to the second frequency may be different from the period corresponding to the first frequency.

According to an embodiment, alternating current power generated by the invertermay be applied to the transmission coil. The capacitormay form a resonance circuit with the transmission coil. The transmission coilmay form a magnetic field based on the applied alternating current power. A portion of the magnetic field (or, magnetic flux) formed by the transmission coilmay pass across a cross-section of the reception coilof the wireless power reception device. As the magnetic field passing across the cross-section of the reception coilchanges over time, an induced electromotive force (e.g., current, voltage, or power) may be generated in the reception coil.

According to an embodiment, the demodulation circuitmay demodulate a signal applied to the transmission coil(e.g., a voltageapplied to both ends of the transmission coil) to output a demodulated signal V. The demodulation circuitmay, for example, identify the amplitude or change in amplitude of the signal applied to the transmission coiland generate the demodulated signal V. The demodulation circuitmay output the demodulated signal Vby, for example, down-converting the frequency of the alternating current power (e.g., 100 to 210 kHz). The wireless power transmission devicemay include a mixer and/or a multiplier circuit for removing carrier components (e.g., 100 to 210 kHz, which are frequencies of alternating current power) for wireless power transmission. Since a waveform in which a component by modulation of the wireless power reception deviceand a component of alternating power of the wireless power transmission deviceare mixed may be applied to both ends of the coilof the wireless power reception device, the frequency component (e.g., 100 to 210 kHz) of the alternating current power may be referred to as a carrier component, and those skilled in the art will understand that the wireless power reception devicedoes not actually generate an electromagnetic wave by mixing modulated data with a carrier wave. Accordingly, the carrier component (e.g., 100 to 210 kHz, which are frequencies of alternating current power) may be removed from the voltageat both ends of the transmission coil. The demodulation circuitmay additionally filter (low pass filter) and output the demodulated signal V. The demodulation circuitmay include a low-pass filter. The demodulation circuitmay filter the voltageat both ends of the transmission coiland then down-convert the alternating current power by a frequency (e.g., 100 to 210 kHz) to generate the demodulated signal V. The amplitude of the voltageat both ends of the transmission coilmay change according to the ASK modulation of the wireless power reception device. According to an embodiment, the controllermay identify the information provided by the wireless power reception device, based on the demodulated signal Voutput by the demodulation circuit. The controllermay, for example, perform analog-to-digital converting (ADC) on the demodulated signal V. The controllermay decode the digital value obtained as a result of the ADC, and may identify the information provided by the wireless power reception deviceaccording to the decoding result. The decoding method may be based on, for example, the Qi standard, but those skilled in the art will understand that there is no limitation thereto. In the example embodiment described above, the demodulation circuitis described as performing frequency down-conversion (e.g., carrier removal) and/or low-pass filtering, and the controllerperforms ADC and/or decoding, but this is merely an example. It will be understood by those skilled in the art that the demodulation circuitmay be implemented to further perform at least one of ADC or decoding according to an embodiment, and the controllermay be implemented to further perform frequency down-conversion (e.g., carrier removal) and/or low-pass filtering according to an embodiment.

According to an embodiment, the wireless power reception devicemay include at least one of a reception coil, a capacitor, a capacitor, a rectifier, a controller, a plurality of capacitors,,, and, a plurality of switches,,, and, a capacitor, a regulator, a capacitor, and/or a charger. For example, the wireless power reception devicemay include a modulation circuit and/or a demodulation circuit. For example, the wireless power reception devicemay perform modulation based on the ASK method, using a modulation circuit (e.g., a plurality of capacitors,,, and, and a plurality of switches,,, and). For example, the wireless power reception devicemay perform demodulation based on the FSK demodulation method using a demodulation circuit.

According to an embodiment, the reception coil, the capacitor, and the capacitormay include a resonance circuit. One end of the capacitormay be connected to the reception coil, and the other end of the capacitormay be connected to one end of the capacitorand one end of the rectifier. One end of the capacitormay be connected to the other end of the capacitor, and the other end of the capacitormay be connected to the other end of the reception coil. For example, the capacitormay be connected in parallel to the circuit formed by the reception coiland the capacitorbeing connected in series. The other end of the capacitormay be connected to the other end of the rectifier.

According to an embodiment, the rectifiermay include a plurality of switches S, S, S, and Sconfiguring a full bridge circuit. One end of the resonance circuit may be connected to a connection point between the switches Sand S, and the other end of the resonance circuit may be connected to a connection point between the switches Sand S. The rectifiermay convert the alternating current power received through the reception coilinto direct current power. The controllermay control the on/off state of the plurality of switches S, S, S, and Sto allow the alternating current power to be converted to direct current power.

According to an embodiment, a capacitorand a regulatormay be connected to the rectifier. One end of the capacitormay be grounded. The regulatormay perform conversion (e.g., buck conversion and/or boost conversion) and/or regulation of the voltage of the rectified power output from the power conversion circuit.

According to an embodiment, the chargermay charge a battery (e.g., the batteryin) using power converted and/or regulated by the regulator. According to an embodiment, the chargermay control the voltage and/or current to charge the battery according to the charging mode of the battery (e.g., a constant current (CC) mode, a constant voltage (CV) mode, or a quick charge mode). Depending on the implementation, a PMIC (not shown) may be connected to the regulatorin place of the charger.

According to an embodiment, the controllermay perform modulation in response to the information to be provided, using a modulation circuit (e.g., a plurality of capacitors,,, and, and a plurality of switches,,, and). The controllermay determine a capacitor to perform modulation among the plurality of capacitors,,, and. According to a capacitor to perform modulation, a difference in amplitude of the voltagesensed by the wireless power transmission devicemay change. For example, when the modulation is performed using only one capacitor, it is assumed that the difference in the amplitude of the voltagesensed by the wireless power transmission device(e.g., the difference between a maximum amplitude of the voltagewhile the switchis in the on state and a maximum amplitude of the voltagewhile the switchis in the off state) is a first value. In this case, the capacitors,,are not used for modulation, so that the switches,, andmay remain in the off state. On the other hand, when modulation is performed using the capacitorand the capacitor, the difference in amplitude of the voltagesensed by the wireless power transmission device(e.g., the difference between a maximum amplitude of the voltagewhile the switchesandare in the on state and a maximum amplitude of the voltagewhile the switchesandare in the off state) is a second value, which may be greater than the first value. In this case, the capacitorsandare not used for modulation, and thus the switchesandmay remain in the off state. The wireless power reception devicemay adjust the degree of modulation (or, the depth of modulation) by adjusting a capacitor to perform modulation among the plurality of capacitors,,, and. As described above, the controllermay output and/or refrain from outputting at least some of the control signals CMA, CMA, CMB, and CMBso that the switches corresponding to the undetermined capacitors remain in the off state while performing modulation using the determined capacitors. For example, the capacitance of the capacitormay be smaller than the capacitance of the capacitor, and the capacitance of the capacitormay be smaller than the capacitance of the capacitor, but this is merely an example and there is no limitation on the magnitude of the capacitances, and they may be the same.

As described above, modulation in the wireless power reception devicemay result in a difference in the amplitude of the voltageat the transmission coil(e.g., a difference between a maximum amplitude while the at least one switch in the wireless power reception deviceis in the on state and a maximum amplitude while the at least one switch in the wireless power reception deviceis in the off state). The difference in the amplitude of the voltageat the transmission coilaccording to the modulation may cause a change in the voltage applied to the capacitors included in the wireless power transmission device. For example, a capacitor to which a direct current voltage is applied is preferably applied with a voltage of a constant value, but the voltage applied to that capacitor may also change in response to modulation of the wireless power reception device.

is a diagram illustrating various phases of a wireless power transmission system according to an embodiment.

Referring to, the phases of the wireless power transmission system may include at least one of a selection phase, a ping phase, an identification and configuration phase, a negotiation phase, and/or a power transmission phase. The phases of the wireless power transmission system may conform to, for example, but are not limited to, the Qi standard.

The wireless power transmission deviceaccording to an embodiment may perform an operation corresponding to at least one of the phases of. The wireless power transmission deviceaccording to an embodiment may not perform an operation corresponding to at least one of the phases of.

According to an embodiment, in the selection phase, the wireless power transmission devicemay monitor whether an object (e.g., the wireless power reception deviceor a foreign object) exists. For example, the wireless power transmission devicemay detect the object (e.g., the wireless power reception deviceor the foreign object), based on the application of a ping signal. Based on the detection of the object (e.g., the wireless power reception deviceor the foreign object), the wireless power transmission devicemay transition to the ping phase. In the ping phase, the wireless power transmission devicemay identify whether the detected object (e.g., the wireless power reception deviceor the foreign object) is a receiver (e.g., the wireless power reception device). For example, the wireless power transmission devicemay apply a digital ping signal to the transmission coil. Based on receiving a response corresponding to the digital ping signal, the wireless power transmission devicemay identify that the detected object is a receiver (e.g., the wireless power reception device). The wireless power transmission devicemay perform at least one operation corresponding to the identification and configuration phasewith the wireless power reception device, and the corresponding operation may follow, for example, but not limited to, the Qi standard. For example, the wireless power transmission devicemay receive, from the wireless power reception device, an identification packet and/or a configuration packet. For example, the identification packet may include information about a version of a standard (e.g., a wireless power consortium (WPC) version) and/or a unique code of a terminal manufacturer. For example, the configuration packet may include information about a power class and/or power to be required. Based on the identification packet and/or the configuration packet, the wireless power transmission devicemay identify information about a terminal manufacturer, a version of a standard, and/or a maximum received power. As described above, the wireless power transmission deviceand the wireless power reception devicemay perform in-band communication. In case that the wireless power transmission devicefails to acquire data from the wireless power reception device(e.g., fails to identify that valid data is being acquired as a result of demodulation) during application of the digital ping signal, the wireless power transmission devicemay determine that a foreign object has been placed. Upon successful completion of the operations in the identification and configuration phase, the wireless power transmission devicemay perform at least one operation corresponding to the negotiation phase, and the corresponding operation may follow, for example, but not limited to, the Qi standard. In the negotiation phase, the wireless power transmission devicemay exchange information (e.g., parameters) for transmitting power with the wireless power reception device. After the negotiation phase, the wireless power transmission devicemay enter the power transmission phaseand may apply power for charging. In the power transmission phase, the wireless power transmission devicemay control the transmission of power, based on information (e.g., parameters) received from the wireless power reception device.

The operations of the wireless power transmission devicemay be described in greater detail with reference to the embodiments described above (e.g., the example embodiments of) and embodiments which will be described below (e.g., the example embodiments of). Each of these example embodiments is provided in separate drawings and in separate paragraphs, but this is for convenience of description only, and at least some of the example embodiments described above and at least some of the example embodiments which will be described later may be applied together. At least some of the example embodiments described above and at least some of the example embodiments which will be described below may be omitted.

Referring to the example embodiments which will be described later (e.g., the example embodiments of), loss power of the wireless power transmission deviceand identification of foreign objects based on loss power will be described.

is a flowchart illustrating an example method of operating a wireless power transmission device according to an embodiment.is a cross-sectional view illustrating example misalignment of a wireless power transmission system according to an embodiment.are graphs illustrating loss power according to an embodiment.

With reference to, mutual loss power and total loss power may be described.is a cross-sectional view of a wireless power transmission deviceand a wireless power reception device. In, the wireless power transmission devicemay include a ferrite, a friendly metal, and a transmission coil. The friendly metalis a metal included in the wireless power transmission device, and there are no restrictions on where the friendly metalis disposed. In, the wireless power reception devicemay include a reception coil, a ferrite, and a friendly metal. The friendly metalis a metal included in the wireless power reception device, and there are no restrictions on where the friendly metalis disposed. In the following, friendly metals (e.g., reference numerals,,, andin) may include the friendly metalof the wireless power transmission device, the friendly metalof the wireless power reception device, the transmission coil, and/or the reception coil.illustrates the presence of a foreign objecton the wireless power reception device. In, mutual magnetic fluxconnected between the transmission coilof the wireless power transmission deviceand the reception coilof the wireless power reception devicemay be formed along the center of the reception coil, even when a misalignment of the wireless power transmission deviceand the wireless power reception deviceoccurs. For example, the mutual magnetic fluxmay be magnetic flux interlinked with the reception coiland inducing a voltage among the magnetic fluxes generated by the transmission coil. For example, when two coils (e.g., the transmission coiland reception coil) share the same magnetic field, the shared magnetic field (e.g., mutual flux) may act as a medium to deliver information.are graphs illustrating transmission current and loss power (e.g., total loss power in, and mutual loss power in) of the transmission coilof the wireless power transmission device. In, “r” may be a value corresponding to a misalignment of the wireless power transmission deviceand the wireless power reception device(e.g., a distance [mm] corresponding to the misalignment). The transmission current may be a current flowing in the transmission coil. The total loss power may include the loss power generated in the friendly metal (e.g., reference numerals,,, and/orof) and/or the foreign objectby the magnetic flux of the transmission coil, the magnetic flux of the reception coil, and the mutual magnetic flux connected between the transmission coiland the reception coil(e.g., reference numeralin). The mutual loss power may include loss power generated in the friendly metal (e.g., reference numerals,,, and/orof) and/or the foreign objectby the mutual magnetic flux (e.g., reference numeralof) connected between the transmission coiland the reception coil. The total loss power (e.g., P) may be the sum of the mutual loss power (e.g., P), the TX loss power (e.g., P), and the RX loss power (e.g., P) (e.g., Equation 1).

The mutual loss power may be proportional to the square of the mutual current (e.g., I) (e.g., Equation 2).

In Equation 2, Rmay be a mutual resistance. The mutual resistance may be a resistance corresponding to the mutual magnetic flux (e.g., reference numeralin) connected between the transmission coiland the reception coilin a T-type equivalent circuit of loss power. The mutual resistance may be calculated by Equation 2, based on the mutual loss power and mutual current.

The mutual current may be the sum (e.g., sum of vectors) of the transmission current and the reception current. The transmission current may be a current flowing in the transmission coil. The reception current may be a current flowing in the reception coil. For example, the mutual current (e.g., I), the transmission current (e.g., I), and the reception current (e.g., I) may satisfy Equation 3.

In Equation 3, φ may be a phase difference between the transmission current and the reception current.

Referring to, even if misalignment of the wireless power transmission deviceand the wireless power reception deviceoccurs, the change in the reluctance (e.g., magnetoresistance) of the flux path that determines the magnitude of the mutual fluxmay be less than the total flux generated by the transmission coil. Accordingly, the mutual loss power (e.g., P) may have a linearity with respect to the square of the transmission current (e.g., I) of the transmission coil(e.g., Equation 4).

The TX loss power (e.g., P) of Equation 1 may be loss power by the transmission current (e.g., I) in a T-type equivalent circuit of the loss power. An estimated value (e.g., P) of the TX loss power (e.g., P) may be calculated by Equation 5.